Handheld battery powered electronic devices such as tablets and smartphones have been in wide use in recent years, with usage rates that are ever increasing, and with additional functionality being added on a regular basis.
A common type of voltage regulator used in such electronic devices is known as a low dropout (LDO) regulator, which can operate with a small input to output differential voltage, and which provides a high degree of efficiency and heat dissipation. A typical LDO regulator includes an error amplifier that controls a field effect transistor (FET) to cause the FET to sink or source current from or to an output node. One input of the error amplifier receives a feedback signal, while the other receives a reference voltage. The error amplifier controls the power FET so as to maintain a constant output voltage.
Such voltage regulators may be used to power various components of the electronic devices, such as systems on a chip and analog to digital converters. For certain such components, it may be desirable for a LDO regulator to be able to both sink and source current from and to an output node to produce a high degree of accuracy of signal output to the output node. In addition, it is desirable for the error amplifier to have the DC characteristics of low power requirements and a low offset, and to have the AC characteristic of high gain. Therefore, further developments in this area are desirable.